CN111884600A - Doherty power amplifier suitable for 5G base station and main power amplifier output matching structure - Google Patents

Abstract

The invention relates to a Doherty power amplifier suitable for 5G base stations and an output matching structure of the main power amplifier. The Doherty power amplifier mainly includes: a power divider, a class F power amplifier and a class C power amplifier, and signals enter the F through the power divider at the same time. A class power amplifier and a class C power amplifier, the class F power amplifier is the main power amplifier, and the class C power amplifier is the auxiliary power amplifier. When the class C power amplifier is not turned on, the class F power amplifier provides the entire amplifier at the fallback point. Efficiency, after the class C is turned on, it provides output power and PAE together with the class F power amplifier, and applies dynamic power division, so that the PAE has a higher value in the entire fallback interval; at the same time, in order to solve the requirement of miniaturization of 5G base stations , an output matching structure integrating second harmonic, third harmonic and fundamental wave matching is proposed, which reduces the complexity of the circuit and facilitates the efficient and miniaturized operation of the power amplifier.

Description

A Doherty Power Amplifier and Main Power Amplifier Output Matching Suitable for 5G Base Stations structure

Technical field:

The invention belongs to the technical field of wireless communication, and in particular relates to a Doherty power amplifier suitable for 5G base stations and an output matching structure of the main power amplifier.

Background technique:

With the advent of the 5G era and the gradual commercialization of 5G products, the entire industry has put forward higher requirements for RF power amplifiers, such as higher efficiency, larger power back-off range, and smaller size. Technology, the power amplifier using the Doherty structure can meet the above requirements to a certain extent. The Doherty power amplifier is generally composed of two power amplifiers. The signal enters the two amplifiers at the same time through the power divider. The two power amplifiers work in class AB and class C respectively. The main power amplifier works in class AB, and the auxiliary power amplifier works in class C. When the class C power amplifier is not turned on, the class AB power amplifier provides the efficiency of the whole amplifier at the back-off point, and then the class C is turned on to jointly provide the output power and PAE. Due to this working principle, the Doherty structure power amplifier can provide a certain range of power back-off And in the entire fallback range, the power amplifier can have a higher PAE. In order to obtain higher efficiency, the main power amplifier can also be replaced by a class F power amplifier. The class F power amplifier matches the harmonics on the basis of the class AB power amplifier, so that the PAE can be improved higher on the basis of the class AB power amplifier. . However, on the basis of fundamental wave matching, Class F power amplifiers add second, third and other harmonic matching networks, which often make the circuit large and complex, which is not conducive to the miniaturization of 5G base station power amplifiers.

Invention content:

The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies. To this end, an object of the present invention is to provide a Doherty power amplifier suitable for 5G base stations and a main power amplifier output matching structure, characterized in that: the Doherty power amplifier includes a power divider, a class F power amplifier and a class C power amplifier , the signal enters the F-class power amplifier and the C-class power amplifier simultaneously through the power divider, the F-class power amplifier is the main power amplifier, the C-class power amplifier is the auxiliary power amplifier, and the F-class power amplifier is not turned on. The power amplifier provides the efficiency of the entire amplifier at the back-off point, and the class C power amplifier is turned on to provide the output power and PAE together with the class F power amplifier.

Preferably, the class F power amplifier includes a main power amplifier output matching structure, and the main power amplifier output matching structure integrates second harmonic, third harmonic and fundamental wave matching.

Preferably, the Doherty power amplifier applies dynamic power division and a transistor output power ratio of 1:3, the backoff range can reach 12dbm, and the PAE has a high value in the entire backoff range.

A main power amplifier output matching structure, the main power amplifier output matching structure is composed of a microstrip line, uses the characteristic impedance of the microstrip line to match the fundamental wave, and uses the electrical length of the microstrip line to match the second and third harmonics, specifically including TLIN1, TLIN2, TLIN3, TLIN4, TLIN5 and TLIN6, wherein TLIN1 and TLIN2 are connected in parallel relationship, TLIN3 is connected in parallel with TLIN2, TLIN4, TLIN5 respectively, TLIN4, TLIN5 are also in parallel relationship, the L-shaped structure composed of TLIN1 and TLIN2 Used for matching slightly less than the third harmonic frequency, the TLIN4 is used for matching slightly greater than the third harmonic frequency, the TLIN5 is used for matching the second harmonic frequency, TLIN1, TLIN2, TLIN3, TLIN4, TLIN5 and TLIN6 The characteristic impedance of is used to match the fundamental wave.

Preferably, the electrical length of TLIN1 and TLIN2 in the output matching structure of the main power amplifier is 30 degrees, and the electrical length of the third harmonic is 90 degrees. At the open circuit of TLIN2, the impedance of the third harmonic is infinite. The impedance value of the impedance transformation becomes 0. Similarly, through the transformation of TLIN1, the impedance value is infinite, and the third harmonic of the drain end is open-circuited. The electrical length of the TLIN5 is 45°. For the second harmonic, its electrical length is It is 90°. After the second harmonic passes through TLIN4, the impedance changes from infinity to 0. Adjust the electrical length of TLIN4 so that the total electrical length of TLIN2 and TLIN4 is 90°. For the second harmonic, it is 180°. The second harmonic is short-circuited, the TLIN6 and TLIN5 form a harmonic trap, which can prevent the influence of the right circuit on the harmonic impedance.

Preferably, the output matching structure combines the concept of harmonic traps, and adds the matching of the third harmonic on the original basis of the concept of harmonic traps, which is equivalent to performing the second matching on the third harmonic, using microstrip In the process of line length matching the second and third harmonics, the first time tends to match the frequency slightly larger than the third harmonic, and the first time tends to be slightly smaller than the third harmonic, that is, the robustness of the output matching structure to the transistor package, parasitic parameters, and more The two outgoing microstrip lines further improve the flexibility of the fundamental wave matching circuit, so that the harmonic and fundamental wave can be matched simultaneously by a whole circuit.

Description of drawings

FIG. 1 is a circuit diagram of an embodiment of the invention

Fig. 2 is the DohertyPAE efficiency diagram of the embodiment of the invention

FIG. 3 is a diagram of the output power of Doherty according to an embodiment of the invention

Detailed ways:

The present invention will be further explained below in conjunction with the accompanying drawings and embodiments.

Example 1

Referring to FIG. 1, the Doherty power amplifier includes a power divider 1, a class F power amplifier 2 and a class C power amplifier 3, and the signal enters the class F power amplifier 2 and the class C power amplifier 3 through the power divider 1 at the same time. The class power amplifier 2 is the main power amplifier, and the class C power amplifier 3 is the auxiliary power amplifier. When the class C power amplifier 3 is not turned on, the efficiency of the whole amplifier at the back-off point is provided by the class F power amplifier 1. The class C power amplifier 3 After it is turned on, it provides output power and PAE together with the class F power amplifier 1. In order to obtain higher efficiency in the embodiment of the present invention, the main power amplifier uses a class F power amplifier to replace the class AB power amplifier, which can improve the PAE higher on the basis of the class AB.

The class F power amplifier 1 includes a main power amplifier output matching structure 4, and the output matching structure 4 of the class F power amplifier 1 integrates the second harmonic, the third harmonic and the fundamental wave matching. The entire output matching structure 4 is composed of microstrip lines. The characteristic impedance of the microstrip line is used to match the fundamental wave, and the electrical length is used to match the second and third harmonics. It combines the concept of harmonic traps and is based on the original concept of harmonic traps. The matching of the third harmonic is added to the above, which is equivalent to the second matching of the third harmonic. In the process of matching the second and third harmonics with the electrical length of the microstrip line, the frequency of the first order tends to be slightly larger than the third harmonic, and the first order tends to match. It is slightly smaller than the third harmonic, which can increase the robustness of the output matching structure to transistor packaging and parasitic parameters, and the extra two microstrip lines improve the flexibility of the fundamental matching circuit, so that a whole The circuit completes the matching of harmonics and fundamental waves at the same time.

The output matching structure 4 includes TLIN1, TLIN2, TLIN3, TLIN4, TLIN5 and TLIN6, wherein the L-shaped structure composed of TLIN1 and TLIN2 is used for matching slightly less than the third harmonic frequency, TLIN4 is used for matching slightly greater than the third harmonic frequency, TLIN5 is used to match the second harmonic frequency, and the characteristic impedance of TLIN1-TLIN6 is used to match the fundamental wave. Among them, the electrical length of TLIN1 and TLIN2 is 30 degrees. For the third harmonic, the electrical length is 90 degrees. At the open circuit of TLIN2, the impedance of the third harmonic is infinite. After the impedance transformation of TLIN2, the impedance value becomes 0. After the transformation of TLIN1, its impedance value is infinite, and the third harmonic open circuit at the drain end is realized. The electrical length of TLIN5 is 45°. For the second harmonic, its electrical length is 90°. Then the impedance of the second harmonic passes through TL4 and changes from infinity to 0. By adjusting the electrical length of TLIN4, the total length of TLIN2 and TLIN4 is adjusted. The electrical length is 90°, and it is 180° for the second harmonic, then the second harmonic short circuit is realized at the drain end. TLIN6 and TLIN5 form a harmonic trap, which can prevent the influence of the right circuit on the harmonic impedance. . The circuit structure is that TLIN1 and TLIN2 are connected together through a parallel relationship, TLIN3 is connected in parallel with TLIN2, TLIN4, and TLIN5 respectively, and TLIN4 and TLIN5 are also connected in parallel.

Referring to Fig. 2 and Fig. 3, the present invention also applies dynamic power division and a transistor output power ratio of 1:3 on the basis of the above innovation, the fallback range can reach 12dbm, and the PAE is relatively high in the entire fallback range. It can be seen that the back-off range of the power amplifier of the present invention can reach 12dbm, and in the whole back-off range, the PAE has a higher level, compared with the ones manufactured by foreign RF amplifier companies (qrovo, etc.). Products, the PAE can be about 10% higher, and in the actual manufacturing process, the robustness of the product will be higher than similar products, both the advantages of stability, high efficiency, and easy miniaturization.

Claims (6)

1. a Doherty power amplifier suitable for 5G base station, it is characterized in that: described Doherty power amplifier comprises power divider 1, F-class power amplifier 2 and C-class power amplifier 3, and the signal enters the described power divider 1 simultaneously. Class F power amplifier 2 and class C power amplifier 3, the class F power amplifier 2 is the main power amplifier, and the class C power amplifier 3 is the auxiliary power amplifier. When the class C power amplifier 3 is not turned on, the class F power amplifier 2 provides the entire power The efficiency of the amplifier at the back-off point, the class C power amplifier 3 provides output power and PAE together with the class F power amplifier after being turned on. 2. A Doherty power amplifier suitable for 5G base stations, characterized in that: the Class F power amplifier 1 includes a main power amplifier output matching structure 4, and the main power amplifier output matching structure integrates second harmonics, third harmonics and fundamental matching. 3. A Doherty power amplifier suitable for 5G base stations, characterized in that: the Doherty power amplifier applies dynamic power division, and a transistor output power ratio of 1:3, the fallback range can reach 12dbm, and the PAE falls back in the entire fallback. There are higher values in the interval. 4. a main power amplifier output matching structure, it is characterized in that: described main power amplifier output matching 4 structure is made up of microstrip line, utilizes microstrip line characteristic impedance to match fundamental wave, and utilizes microstrip line electric length to match two times, three times Harmonics specifically include TLIN1, TLIN2, TLIN3, TLIN4, TLIN5 and TLIN6, where TLIN1 and TLIN2 are connected in parallel, TLIN3 is connected in parallel with TLIN2, TLIN4, TLIN5, TLIN4, TLIN5 are also in parallel, the TLIN1 , the L-shaped structure composed of TLIN2 is used for matching slightly less than the third harmonic frequency, the TLIN4 is used for matching slightly greater than the third harmonic frequency, the TLIN5 is used for the matching of the second harmonic frequency, TLIN1-TLIN6 The characteristic impedance is used to match the fundamental wave. 5. a kind of main power amplifier output matching structure according to claim 4, is characterized in that: in described main power amplifier output matching structure 4, TLIN1 and TLIN2 electrical length is 30 degrees, and its electrical length is 90 degrees for the third harmonic °, at the open circuit of TLIN2, the impedance of the third harmonic is infinite. After the impedance transformation of TLIN2, the impedance value becomes 0. Similarly, through the transformation of TLIN1, the impedance value is infinite, and the third harmonic of the drain is open. The electrical length of TLIN5 is 45°. For the second harmonic, its electrical length is 90°. After the second harmonic passes through TLIN4, the impedance changes from infinity to 0. Adjust the electrical length of TLIN4 to make the total of TLIN2 and TLIN4. The electrical length is 90°, and it is 180° for the second harmonic. The drain end realizes the second harmonic short circuit. The TLIN6 and TLIN5 form a harmonic trap, which can prevent the influence of the right circuit on the harmonic impedance. 6. A main power amplifier output matching structure according to claim 4, characterized in that: the main power amplifier output matching structure 4 combines the concept of harmonic traps, and increases the harmonic trap concept on the original basis. The matching of the third harmonic is equivalent to the second matching of the third harmonic. In the process of matching the second and third harmonics with the electrical length of the microstrip line, the frequency of the first time tends to be slightly larger than the third harmonic, and the first time tends to be slightly smaller than the third harmonic. The third harmonic is to increase the robustness of the output matching structure to the transistor package and parasitic parameters. The extra two microstrip lines improve the flexibility of the fundamental wave matching circuit, so that a whole circuit can simultaneously complete the harmonic detection. match with the fundamental wave.

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